Chicago Bears: What You Need to Know Heading into Week 4

After another close call, the Chicago Bears are 3-0 with their second straight road game on the horizon, as they'll travel to Detroit for a key NFC North game.

While the Green Bay Packers were—and probably still are—considered to be the favorites in the NFC North division this year, it is the Bears and the Lions who sit on top. Chicago currently has a one-game lead on the Lions, but that could change on Sunday if the Bears don't play better than they have in the last two weeks.

It might be too early to call any game a "must win," but every divisional game should be considered extremely important. Even if the Bears don't end up winning the NFC North, they need as many NFC wins as possible to get an edge in seeding for the playoffs.

Here are a few things you need to know about the Bears and their opponents entering Week 4.

Charles Tillman isn't what he was in 2012

Perhaps the biggest thing the Bears had going for them when they faced the Lions last year was that they had one of the best cornerbacks in the league defending Calvin Johnson. However, Tillman simply hasn't been the same player this year.

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There are a variety of reasons for this. He struggled with cramps in Week 1 and was beaten for one catch of over 40 yards and a short touchdown reception, then drew a long pass-interference penalty on third down. In Week 2 he hurt his knee, which seemed to affect him in Week 3 as he struggled with the Steelers' quick wide receivers.

Tillman was questionable heading into the game against Pittsburgh and may have been better off not playing. He wasn't able to finish the game and struggled when he was in.

Injuries are part of the league and haven't seemed to bug Tillman much in the past, but he's 32 years old now. The shelf life for NFL cornerbacks differs, but it's possible the Bears' star is nearing his end.

Regardless of his long-term future, the Bears need him to be at his best when he goes against Johnson on Sunday.

Johnson has almost certainly heard about how Tillman shut him down last year—holding him to eight catches for 106 yards in two games—and he'll want to show he can win the matchup this time.

Johnson has had back-to-back 100-yard games and could be in line for another if the Bears don't give Tillman help.

These aren't the 2012 Lions

After an 10-win 2011 campaign, the 2012 Lions fell well short of expectations by winning just four games. The 2013 version seems to be much closer to the 2011 team, as they're already halfway to last year's win total.

While they're still not anywhere near one of the best defensive units, they've actually been stingier than the Bears so far this year. Detroit has been giving up 23 points per game—compared to the 24.7 for the Bears—and have forced seven turnovers, including five interceptions.

Detroit has gotten an instant impact from rookie defensive end Ziggy Ansah, who already has 2.5 sacks. Make no mistake: The Lions defense starts in the middle, where they have two stud defensive tackles in Ndamukong Suh and Nick Fairley.

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Defensively, they're very similar to the Vikings. Their success is predicated on putting pressure on the passer since they're not very strong in the secondary.

The Lions are giving up an average passer rating of just 70.8 so far this year, the eighth-best rate in the league per NFL.com.

Offensively, we're seeing a lot more patience from the Lions, particularly from quarterback Matthew Stafford.

No quarterback has gotten rid of the ball faster than Stafford this season. According to Pro Football Focus (subscription required), Stafford has averaged a league-low 2.18 seconds before attempting to pass. He's gotten rid of the ball in under 2.5 seconds on 74.4 percent of his attempts, by far the highest rate in the league, as Cincinnati's Andy Dalton is second at 67.2 percent.

That means the Bears aren't likely to get a lot of pressure on Stafford unless they get a big lead and he's forced to hold onto the ball longer.

As you see in the screen shot below from Pro Football Focus (subscription required), Stafford has attempted just nine passes which traveled over 20 yards in the air this season:

The result has been just two sacks and two interceptions. He isn't just being a game-manager, however, as he's still managed to be third in the league in yardage with 1,020 through three games, behind only Peyton Manning, Aaron Rodgers and Drew Brees.

When opponents have taken away Johnson, Stafford has effectively gone to other weapons. Nate Burleson is actually the team's leading receiver with 19 catches on just 23 targets. Burleson, however, isn't expected to be available on Sunday after breaking his arm in a car accident early Tuesday morning (according the the Lions team website).

Stafford's accuracy is still a question mark. Despite the fact that he's attempting more short passes on average than any other quarterback, his completion percentage of 63.6 is just 14th-best in the league.

While he doesn't throw a lot of interceptions, the ones he has thrown have hurt. The interception he threw to the Vikings came when his team was in scoring position. Against the Redskins, he had an interception returned for a touchdown.

The Bears defensive backs have to have to be ready for when Stafford's passes are wild, as they'll have excellent opportunities to come away with some big plays.

Pressure is on Collins

The Bears defense suffered a big blow against the Steelers, as Pro Bowl defensive tackle Henry Melton tore his ACL, ending his season, as per ESPN.

That means Nate Collins will have to step into the starting lineup, and the Bears will need him have a big impact this week.

As I touched on earlier, the Lions get rid of the ball quickly, which means the Bears will have to get pressure up the middle if they're going to get to Stafford.

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Collins doesn't have a sack this season, but he was able to hit Ben Roethlisberger last week.

The Bears' pass rush has been unimpressive this season, as they have just five sacks. That—as well as struggles by Tillman and the rest of the secondary—have allowed opposing passers to have an average rating of 89.2 against the Bears, 19th best in the league.

While Collins hasn't brought the quarterback down in the last two years, he's shown good burst when he's been on the field. The question now is if that burst is a permanent part of his game or just because he had rested legs.

In addition to increasing Collins' snaps, the Bears will likely rotate defensive ends Corey Wootton and Julius Peppers inside more often, and we could see undrafted rookie Zach Minter get his first action.

Regardless of who plays, it will be hard for them to be worse than Melton was for the Bears this season. Melton struggled in the team's first three games, putting hardly any pressure on the quarterback, and he's never been known as a great run defender.

The Bears need the interior of their defensive line to hold up against Detroit to help force them to 3rd-and-long situations and then to hurry Stafford.

Pursuit will be key

While they've been throwing underneath a lot, the Lions have also been getting a lot of big plays doing so.

Running backs Joique Bell and Reggie Bush both have two passing plays of over 20 yards off of screen or underneath passes.

While Bush's status is unknown at this point—he missed their game against Washington with a knee injury—Bell has proven he can be dangerous. He's averaged just under 100 yards from scrimmage per game this season and has three touchdowns.

That said, he's not the explosive weapon Bush can be. Bush scored a 77-yard touchdown off of a screen pass in their Week 1 win over the Lions and averages 20.7 yards per reception.

Stafford has had 601 of his yards come after the catch, according to Pro Football Focus (subscription required). That is the highest total and second-highest percentage (58.9 percent, ahead of Matt Ryan's 61.5 percent) in the league.

Stafford is certainly capable of making big plays with his arm, but the Bears have to make sure they don't make it easy on him. They have to make Stafford beat them with throws in tight coverage down the field. When teams do that, Stafford almost always makes big mistakes.